Development of fluorescence lifetime microscope. Two new time-resolved fluorescence microscopy techniques are being developed in the LFD. The first technique uses a frequency-modulated CCD camera to simultaneous determine the lifetime of chromophores over the whole image. The second technique uses two-photon scanning technology coupled with frequency-domain instrument to determine the fluorescence intensity and lifetime distribute in a three dimensional sample volume. These new techniques has been applied in collaborative studies such as DNA-probe interaction, antibody-cell receptor binding, drosophila, embryo development, and oxygen distribute in cells.